Ancient sea creature gives researchers a brainwave
AN ancient sea creature found off the coast of Scotland in 2011 has shed new light on how evolution formed the modern brain.
An international team, including researchers at St Andrews University, have examined the amphioxus, also known as the lancelet, which was thought to be a brainless, faceless fish.
Instead, they found it has a very complex brain that confounds previous understanding of how vertebrate brains evolved.
The research, carried out by the universities of St Andrews, Murcia and Barcelona and Spain’s Centre for Genomic Regulation, is published in the journal PLOS Biology.
It compared the amphioxus brain with current models of brain development in vertebrates, such as chicks and fish.
The research casts doubt on the textbook idea the complex vertebrate brain evolved from a simple three-part brain composed of forebrain, midbrain and hindbrain.
The new research suggests the vertebrate brain originally formed from two parts.
Dr Ildiko Somorjai, of the School of Biology at St Andrews, said: “Amphioxus is an amazing creature that can tell us a lot about how we have evolved.
“Humans have enormous brains with a large number of subdivisions to allow processing of complex information as well as motor control and language.
“Research
in amphioxus tells us that even an outwardly simple brain may have complex regionalisation.
“It also strengthens the position of amphioxus as an important non-vertebrate model for understanding vertebrate evolution.”
Described as a “brainless, faceless fish”, amphioxus was found off the coast of Orkney during a 2011 marine survey and is thought to be among the first animals to have evolved a structure like a backbone, the notochord.
Despite its appearance, amphioxus is not a fish. It has a primitive spinal cord which runs down its back, but no clearly defined face, no bones or jaw and a small brain with a single light-sensing “frontal eye”.
It has changed so little for millions of years that it has been called a “living fossil”.
As the best living proxy for the vertebrate ancestor, amphioxus gives insight into what humanity’s distant ancestor was like.